When Twitter put out its strict new API guidelines, there was some doubt as to whether or not third-party clients like Tapbots' Tweetbot for Mac would even make the cut -- the user caps and other curbs on unofficial apps potentially made it tough to develop competition around a different (and possibly better) experience. That makes today's official appearance of Tweetbot in the Mac App Store as much symbolic as it is practical. While there won't be many significant shocks for those who've been participating in Tweetbot's alpha and beta stages, the finished version gives everyone running OS X Mountain Lion a major and sometimes more advanced alternative to official choices, such as TweetDeck, as well as existing third-party options like Twitterrific. A $20 price doesn't make Tweetbot the cheapest way to buck convention by any means, but it might be worth the investment if you're already committed to Tapbots' iOS apps or want to make a statement on the value of third parties in an ecosystem.